Re: [RFC] Implementation of SCSI dynamic power management

Am Mittwoch, 9. Januar 2008 21:36:20 schrieb Alan Stern:

On Wed, 9 Jan 2008, Oliver Neukum wrote:

quoted

Am Mittwoch, 9. Januar 2008 18:22:51 schrieb Alan Stern:

quoted

On Wed, 9 Jan 2008, Oliver Neukum wrote:

quoted

This has an interesting implication. As the storage driver can share
a device with in principle any other usb driver, we must audit all usb
drivers if we wish to adopt this patch.
All a device's interfaces must be resumed when the storage interface
is resumed. To resume a storage device no memory must be allocated
because that could deadlock.

Maybe people shouldn't enable autosuspend for their swap device...

Good advice, but not sufficient to avoid this problem. The vm may write
out normal dirty cached pages to scsi devices, which affects storage.

For now, I think the best approach is "head-in-the-sand".  There aren't
a lot of USB storage devices partnered with other functions at the
moment.

Very well with exception of the hub driver.
 

But it might be a good idea for all USB drivers to use GFP_NOIO in
their resume pathways.

Yes, we should make this a requirement for every driver henceforth changed
to support autosuspend.

	Regards
		Oliver